Air-launched radio apparatus

ABSTRACT

An air-deliverable package for radio apparatus having a selfdeploying antenna system including a flexible RF radiating element and laterally projecting, flexible ground plane elements which are foldable about a packed main parachute received within a tubular container which, in turn, is detachably connected to the aft end of the package and is separated therefrom by deployment of a pilot chute to enable deployment of the main parachute and the antenna system.

Unite w" States aent Herring et al.

AIR-LAUNCHED RADIO APPARATUS Inventors: Theodore C. Herring, New Hope;Ernest F. Bracht, Jenkintown; Robert E. Ainslie, Glenside; Eugene M.Todd, Doylestown; Joseph J. Franz, Philadelphia, all of Pa.

Assignee: The United States of America as represenced by the Secretaryof the Army Filed: Sept; 26, 1967 App]. No.: 670,807

U.S. Cl. ..325/ll2, 102/35, 102/37.1, 102/4 Int. Cl. ..H04b l/02 Fieldof Search ..325/112, 114; 343/706, 897; 244/1, 138

[ 51 Feb. 6, 1973 [56] References Cited UNITED STATES PATENTS 2,551,6095/1951 Kohr et al ..325/112 2,992,793 7/1961 Devantier t 1 ..244/13,273,835 9/1966 Holt et a1 ..244/138 Primary Examiner-Samuel FeinbergAssistant Examiner-Richard E. Berger Att0rneyl-lenry Hansen and E. J.Brower ABSTRACT An air-deliverable package for radio apparatus having aself-deploying antenna system including a flexible RF radiating elementand laterally projecting, flexible ground plane elements which arefoldable about a packed main parachute received within a tubularcontainer which, in turn, is detachably connected to the aft end of thepackage and is separated therefrom by deployment of a pilot chute toenable deployment of the main parachute and the antenna system.

11 Claims, 2 Drawing Figures PATENTED FEB 6 I975 INVENTORS THEODORE C4HERRING ERNEST F. BRACHT ROBERT E. AINSLIE EUGENE M. TODD JOSEPH J.FRANZ I ATTORNEYS AIR-LAUNCHED RADIO APPARATUS The invention describedherein may be manufactured and used by or for the Government of theUnited States of America for governmental purposes without the paymentof any royalties thereon or therefor.

BACKGROUND OF INVENTION This invention primarily relates to radioapparatus which is packaged for delivery from an aircraft to an optimumlocation and which includes a compatible, self-deploying antenna system.Previously known airdelivered radio apparatus has included antennasystems which are subject to damage as by parachute deployment or byimpact or entanglement with trees and other obstructions on the ground.While equipment has been developed for erecting an antenna system oncethe air-delivered apparatus has landed, the inclusion of known antennaerection equipment detrimentally increases the cost, size and weight ofthe apparatus. Additionally, in certain reconnaissance situations, it isdesirable that the apparatus be deliverable with greater certainty to aposition in the intervening space above underlying shrubberyand'undergrowth and below the upper canopy of the trees in a woodedarea.

BRIEF SUMMARY OF INVENTION It is the general purpose of this inventionto provide packaged radio apparatus having a simple, inexpensive,self-deploying antenna system which is deliverable by an aircraft and iscompact, easy to fabricate, and not subject to the defects of previouslyknown air-delivered radio apparatus. Briefly, this is accomplished byproviding a forward package having a self-deploying antenna systemincluding a flexible energy radiating element and a plurality offlexible ground plane elements which are bendable to encircle a packagedmain parachute. The antenna encircled main chute is received within atubular container which is automatically detachable from the forwardpackage for simultaneous deployment of the main chute and the antennasystem. In a more specific sense, the invention comprehends a groundplane antenna array wherein the elements include flexible blades whichare wrapped with insulating tape and are fixed at one end to a hubassembly having a configuration such that the ground plane elements tendto extend generally radially of the package axis and slightly deflectedfrom a plane normal to the package axis for optimum effectiveness.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a longitudinal view of apparatusaccording to the invention with portions broken away; and

FIG. 2 is an isometric view of the apparatus of FIG. 1 as deployedduring descent after launch from an aircraft.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring now to FIG. 1,the apparatus includes radio apparatus which is broadly represented by ablock 11 and may have a power supply such as a battery and desiredelectronic components such as a radio transmitter and a sensor activatedswitch, none of which are shown. The radio apparatus 11 is packagedwithin a forward tubular container 12 of fiberglass. An

apertured nose cone 13, within which may be appropriately mounted asensor such as a microphone, not shown, is fixed to and closes theforward end of the tube 12; and an aluminum antenna hub assembly 14protrudes from and closes the other end of the tube 12.

More particularly, the hub 14 has a generally cylindrical configurationand includes a longitudinally depending annular flange 15 which ispartially received within and is fixed to the aft end of the tube 12 asby screws, not shown. The hub 14 also includes a coaxially-bored bossportion 16 protruding longitudinally of the tube 12 within which isfixed an insulator bushing 17 which, in turn, supports a radio frequencyradiating antenna element 18 extending therefrom. The radiating element18 is made of a strip of resilient, flexible sheet steel, tends to erectitself into an operating position in alignment with the extension of thelongitudinal axis of the tube 12 with the assistance of a shorter,contiguous, flexible steel spring element 18a and is electricallyconnected to the radio apparatus 11 by an insulated lead 19. The hub 14has four symetrically positioned, uniformly inclined surfaces 21extending radially of the axis of the hub 14 from the boss between arespective pair of parallel plates 22 extending longitudinally of thehub 14. The ends of four ground plane antenna elements 23 areelectrically and mechanically connected as by screws, not shown, torespective ones of the surfaces 21 in cantilevered arrangements so thatthe elements 22 normally tend to extend generally radially of the axisof the hub 14 and of the tube 12 in alignment with the respectivesurfaces 21 and the extensions thereof. The elements 23 are made offlexible, resilient steel strips 23a similar to that used in retractabletape measures, and have their free ends wrapped, as indicated in FIG. 2,with tape 24 of plastic impregnated cloth.

The inclination of the surfaces 21 through an angle 0 from a planenormal to the axis of the hub 14 is of a predetermined magnitude such asis shown to insure that an optimum antenna pattern will be obtained.More particularly, the antenna structure shown provides a verticallypolarized, omnidirectional radiation field strength pattern of toroidalconfiguration which is circular in axially normal planes and in axiallyaligned planes extending to either side of the element 18.

Each of the pairs of parallel plates 22 supports a respective roller 25which extends therebetween in spaced relation to the surface 21 so thatthe respective ground plane element 23 may be interposed. Moreparticularly, the rollers 25 are positioned adjacent a longitudinalextension of the tube 12 for serving as guides about which the groundplane elements 23 may be folded toward oppositely directed, abuttingengagement with the free end of the diametrically opposite element 23 toform transversely arranged loops 26a and 26b. The loops 26a and 26bextend longitudinally from the tube 12 and are large enough to encirclea folded main parachute 27, the free end of the radiating element 18being included in one of the loops 26a.

Additionally, two of the rollers 25 having diametrically opposedpositions are connected to the looped ends of a riser bridle 28 whosemidpoint is connected by a riser 29 to the ends of suspension lines 30which are connected to the main chute 27. It is preferred that thebridle 28 have a sufficient length as shown in FIG. 2

to insure that clearance with respect to the radiating element 18extended in operative position will be provided upon chute deployment.The unfolded main chute 27 preferably has a flat, circular configurationso that the chute will tend to be unstable for a purpose hereinafterexplained. For example, the parachute 27 may be fabricated from 16 nylongores having an isosceles triangular configuration and an apex angle of22% so that the chute 27 lies essentially flat on a planar surface. Thesize of the chute 27 and the length of the suspension lines 30 may beascertained by one skilled in the art as influenced by the weight of thepackage to be suspended therefrom, the air speed at which the apparatusis to be launched, and the desired descent rate according to permissibleimpact loading, as for example, feet per second, so that the chute 27can oscillate without collapsing.

The main chute 27 which is encircled by the flexible antenna elementloops is received within a cardboard tube 31, the forward end of thetube 31 having been slid onto the projecting lateral periphery of thehub 14 and into abuttment with the tube 12 and being secured to the tube12 by a turn of adhesive paper masking tape 32. The tube 31 includes acircular divider 33 of wood which is fixed in a position inwardly of theaft end of the tube 31 adjacent the antenna encircled main chute 27 toform a pilot chute compartment for receiving a spring-loaded, nylonpilot chute 34. A static line 35 interconnects the pilot chute 34 andthe main parachute 27 with the divider 34. The aft end of the tube 31 isprovided at its periphery with a pair of apertured studs 36 and isclosed by a circular cover 37 having apertures through which the studs36 protrude. A pilot chute spring 38 attached at one end to the centerof the square pilot chute 34 is maintained in compression by the cover37 which is held in pilot chute retaining position by a pin 39 extendingthrough the studs 36 and having a lanyard 40 attached thereto.

In assembling the apparatus 10, the bridle 28 is'attached todiametrically opposite rollers 25, and diametrically opposite groundplane elements 23 are folded in overlying relationship to form the loops26a and 26b, the free ends of the antenna elements 22 and 18 being heldto the loops 26a or 26b by a series of turns or loops 41 of papermasking tape. It is important that the width and thickness of the tapeloops 41 be small enough so that deployment of the main chute 27 willcause their failure in order that the antenna elements 18 and 23 bereleased. For example, a single turn of one-quarter inch paper maskingtape which overlaps on one side only of the stacked configuration ofantenna elements encircled thereby has been found to satisfactorily failupon chute deployment. The rollers 25 prevent crimping of the antennaelements 23 during the loop forming process, which crimps could causemechanical failure of the antenna elements 23 or separation thereofduring the deployment of the parachute 27 upon landing. The folded mainchute 27 is then placed within the cage formed by the transverse loops26a and 26b, and the cardboard tube 31 is slid over the elements 23 andattached to the tube 12.

Upon ejection from an aircraft, the lanyard 40 is actuated to remove thespring pin 38 for enabling the pilot chute spring 38 to force theejection of the cover 37 and the pilot chute 34 into the air stream. Thesudden deployment of the pilot chute 34 causes the tape 32 to fail sothat the tube 31 is withdrawn from envelopment of the main chute 27 bythe static line 35. The impinging air stream and the extended staticline 35 cause the main chute 27 to deploy and effect consequentialfailure of the tape loops 41 so that deployment of the antenna elements18 and 23 occurs. The taped covering 24 of the elements 23 not onlyprovides sufficient electrical insulation to prevent harmful electricalcontact between the element 18 and any of the elements 23 but also addsstructural integrity to the flexible elements 23. In the event thatpartial mechanical failure of an element 23 occurs, the tape 24maintains the appropriate length for the element 23. The free ends ofthe elements 23 are freely flexible to permit the descent of the tube 12through tree branches so that the microphone or other sensor carriedthereby may be appropriately positioned in the intervening space betweenthe upper jungle canopy and the underlying shrubs, the main chute 27being entangled in the trees. As indicated above, it is preferred thatthe main chute be unstable in order that the tube 12 will oscillate likea pendulum from vertical alignment during descent so that there is agreater possibility that the suspension lines 30 and/or the main chute27 will become entangled in the tree branches of the upperjungle canopy.

The above described compact apparatus thereby avoids the above indicateddefects of the prior art. A rugged radio apparatus having a simple,inexpensive self-deploying antenna system which is deliverable fromaircraft as desired to the intervening space between the upper canopyand underlying shrubs in a wooded area has been provided by theinvention.

It is to be understood, of course, that the foregoing disclosure relatesonly to a preferred embodiment of the invention and that numerousmodifications or alterations may be made without departing from thespirit and scope of the invention as set forth in the appended claims.

We claim:

1. Apparatus comprising:

a container having an aft end for housing radio apparatus;

radiating antenna element of flexible resilient material connected atone end to and tending to extend from said aft end of said container;

a plurality of ground plane antenna elements each made of flexible,electrically conducting material and having an end connected to said aftend of said container, said elements tending to extend themselvesgenerally radially of an axis for forming a ground plane;

a tube detachably connected at one end to said aft end of saidcontainer; and

a main parachute connected to said container and received within saidtube and encircled by said antenna elements received within said tube.

2. Apparatus according to claim 1 wherein:

said main parachute comprises an unstable chute which, when deployed,tends to nutate said container depending therefrom during descent.

- 3. Apparatus according to claim 2 wherein:

said main parachute has a flat, circular configuration and is connectedto said aft end of said container.

4. Apparatus according to claim 1 further comprising: 1

means for detaching said tube from said container to facilitatedeployment of said main parachute and said antenna elements.

5. Apparatus according to claim 4 wherein said means for detachingincludes:

pilot chute means connected to said tube and received within the otherend thereof; and

adhesive tape means for securing said one end of said tube to saidcontainer until deployment of said pilot chute.

6. Apparatus according to claim 1 further compristape means wrappedabout the free ends of each of said ground plane elements.

7. Apparatus according to claim 1 further comprisa hub assembly securedto said aft end of said container and having said antenna elementsconnected thereto; and

a plurality of guide means connected to said hub assembly and positionedadjacent a respective one of said one end of said ground plane elementsfor providing a guide about which said ground plane elements are bent toextend longitudinally within said tube from main parachute encirclingconfigurations.

8. Apparatus according to claim 7 wherein:

said hub assembly has inclined aft surfaces forming a generallytruncated conical configuration radially extending towards its lateralperiphery; and

said one ends of said ground plane elements being fixed to and tendingto extend generally radially along said inclined surfaces for providinga vertically polarized, omnidirectional radiation field strength patternof toroidal configuration.

9. Apparatus according to claim 7 wherein said guide means includes:

a plurality of pairs of parallel plates, each pair being fixed at theirperipheries to said hub assembly on opposite sides of a respective oneof said ground plane elements; and

a like plurality of rollers each connected to extend between said platesin a respective pair and adjacent said respective ground plane elements,said main parachute being connected to at least one of said rollers.

10. Apparatus according to claim 9 wherein:

said ground plane elements are arranged in diametrically opposed pairs;and

paper tape means securing the free ends of opposing ground planeelements together to form main chute encircling loops, said tape meansbeing breakable to release said elements in response to deployment ofsaid main chute.

l1. Apparatus according to claim 10 further comprising:

a divider secured within said tube and dividing same into a pilot chutecompartment and a main chute compartment;

a pilot chute received within said pilot chute compartment and connectedto said divider;

means connecting said divider with the center said main chute foractuating deployment of said main chute upon withdrawal of said tubefrom said main chute receiving position in response to deployment ofsaid pilot chute.

1. Apparatus comprising: a container having an aft end for housing radioapparatus; a radiating antenna element of flexible resilient materialconnected at one end to and tending to extend from said aft end of saidcontainer; a plurality of ground plane antenna elements each made offlexible, electrically conducting material and having an end connectedto said aft end of said container, said elements tending to extendthemselves generally radially of an axis for forming a ground plane; atube detachably connected at one end to said aft end of said container;and a main parachute connected to said container and received withinsaid tube and encircled by said antenna elements received within saidtube.
 1. Apparatus comprising: a container having an aft end for housingradio apparatus; a radiating antenna element of flexible resilientmaterial connected at one end to and tending to extend from said aft endof said container; a plurality of ground plane antenna elements eachmade of flexible, electrically conducting material and having an endconnected to said aft end of said container, said elements tending toextend themselves generally radially of an axis for forming a groundplane; a tube detachably connected at one end to said aft end of saidcontainer; and a main parachute connected to said container and receivedwithin said tube and encircled by said antenna elements received withinsaid tube.
 2. Apparatus according to claim 1 wherein: said mainparachute comprises an unstable chute which, when deployed, tends tonutate said container depending therefrom during descent.
 3. Apparatusaccording to claim 2 wherein: said main parachute has a flat, circularconfiguration and is connected to said aft end of said container. 4.Apparatus according to claim 1 further comprising: means for detachingsaid tube from said container to facilitate deployment of said mainparachute and said antenna elements.
 5. Apparatus according to claim 4wherein said means for detaching includes: pilot chute means connectedto said tube and received within the other end thereof; and adhesivetape means for securing said one end of said tube to said containeruntil deployment of said pilot chute.
 6. Apparatus according to claim 1further comprising: tape means wrapped about the free ends of each ofsaid ground plane elements.
 7. Apparatus according to claim 1 furthercomprising: a hub assembly secured to said aft end of said container andhaving said antenna elements connected thereto; and a plurality of guidemeans connected to said hub assembly and positioned adjacent arespective one of said one end of said ground plane elements forproviding a guide about which said ground plane elements are bent toextend longitudinally within said tube from main parachute encirclingconfigurations.
 8. Apparatus according to claim 7 wherein: said hubassembly has inclined aft surfaces forming a generally truncated conicalconfiguration radially extending towards its lateral periphery; and saidone ends of said ground plane elements being fixed to and tending toextend generally radially along said inclined surfaces for providing avertically polarized, omnidirectional radiation field strength patternof toroidal configuration.
 9. Apparatus according to claim 7 whereinsaid guide means includes: a plurality of pairs of parallel plates, eachpair being fixed at their peripHeries to said hub assembly on oppositesides of a respective one of said ground plane elements; and a likeplurality of rollers each connected to extend between said plates in arespective pair and adjacent said respective ground plane elements, saidmain parachute being connected to at least one of said rollers. 10.Apparatus according to claim 9 wherein: said ground plane elements arearranged in diametrically opposed pairs; and paper tape means securingthe free ends of opposing ground plane elements together to form mainchute encircling loops, said tape means being breakable to release saidelements in response to deployment of said main chute.